Abdominal Imaging

ª Springer Science+Business Media, LLC 2008 Published online: 15 August 2008

Abdom Imaging (2009) 34:648–661 DOI: 10.1007/s00261-008-9449-8

Torsion of the spermatic cord: the main gray-scale and doppler sonographic signs De´cio Prando Av. Repu´blica do Libano 990, Sao Paulo, SP 04502-001, Brazil

Abstract Scrotal ultrasonography (US) is usually the initial imaging modality for evaluating patients who present with acute pathologic conditions of the scrotum. Acute epididymitis, acute epididymo-orchitis, torsion of the spermatic cord (TSC), and other acute scrotal abnormalities may have similar findings at clinical examination. Pain and swelling make the clinical examination difficult, sometimes practically impossible, potentially resulting in management delays. The objective of this review is to summarize the main clinical signs of the TSC and to illustrate and briefly discuss the US features of this entity, including gray-scale imaging, color Doppler with spectral analysis, and power Doppler sonography. Although TSC can occur at any age, it is most common in adolescent boys. The intensity of the symptoms and the US findings vary with the duration of the torsion, number of twists in the spermatic cord (degree of rotation), and how tightly the vessels of the cord are compressed. An enlarged, more spherical, and diffusely hypoechogenic testis without detectable arterial and venous testicular flow at color and power Doppler US is considered diagnostic of acute testicular ischemia. The presence of a color or power Doppler signal in one part of the testis does not exclude TSC. Positive blood flow but significantly diminished, usually near or inside the mediastinum, may be found, mainly in the partial or incomplete TSC. Identification of a large echogenic extratesticular mass distal to the site of the torsion, frequently misinterpreted as a chronic epididymitis, can be the key to the diagnosis of TSC. When a small arterial sign is found a low amplitude waveform is present with an increased resistive index on the affected side due to a diminished, absent, or reversed diastolic flow. Gray-scale imaging, color Doppler, power Doppler and pulsed Doppler with spectral analysis are very effective to make or exclude the diagnosis of TSC.

Correspondence to: De´cio Prando; email: [email protected]

Key words: Ultrasound—Doppler studies—Testis—Scrotum—Torsion—Color Doppler sonography

Torsion of the spermatic cord is the most common cause of an acutely painful scrotum in boys. Pain and swelling make the clinical examination very difficult [1]. If this diagnosis cannot be ruled out, prompt surgical exploration is the preferred option [2–4]. The intensity of the symptoms and the degree of testicular ischemia depend not only on the duration of the torsion, but also on the number of twists in the spermatic cord and how tightly the vessels of the cord are compressed [5, 6]. Diagnosis is important because torsion requires prompt surgical intervention to save the testis, whereas other diseases usually can be treated medically [7]. The salvage rate of the torsed testes when surgery is performed within 5 h of the onset of pain is 80–100% [8, 9]. When performed within 6–12 h after torsion, 70%; however, if the surgery is delayed more than 12 h the salvage rates decreases to 20% [4, 8, 9]. Gray-scale imaging and Color Doppler

Fig. 1. Acute torsion of the left spermatic cord in a 14-yearold boy. (A) Longitudinal sonogram of the normal right testis. (B) Longitudinal sonogram of the enlarged mildly hypoechoic torsed left testis. Same scale as in (A).

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Fig. 2. Good identification of the lobar architecture due to interstitial and septal edema. (A) Longitudinal sonogram of the symptomatic hypoechoic right testis shows thickened hypoechoic septa with a radial orientation in relation to the mediastinum (RM). Although this is an axial image of the right hemi-scrotum, the image shows a longitudinal view of the affected testis due to its near-horizontal position into the hemi-scrotal sac. There is a

small posterior and inferior hydrocele (*). (B) Axial position of the transducer in the left hemi-scrotum and transverse sonogram of the normal left testis and its normal echogenic mediastinum (LM). (C) The cut, surgical specimen shows an extensive hemorrhagic infarct of the torsed testis. (D) A different patient with TSC. Transverse sonogram of the left torsed testis. Thickened hypoechoic septa with a radial orientation.

ultrasound are effective in helping to make or exclude the diagnosis of testicular torsion mainly when there is an overlap of signs and symptoms of torsion of the spermatic cord and acute epididymitis, epididymo-orchitis, torsion of the appendix testis, strangulated hernia and traumatic hemorrhagic hydrocele [3, 4, 6]. The main clinical signs and US guidelines for evaluating patients with acute, subacute, and chronic TSC will be demon-

strated and discussed, including gray-scale, pulsed Doppler US with spectral analysis, and color and power Doppler sonography.

Mechanism of torsion About 60% of the patients who suffer testicular torsion have congenital anomalies in both testes, involving

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Fig. 3. The mediastinum is thickened and less echogenic (arrow). (A) Longitudinal sonogram of the enlarged and mildly hypoechoic symptomatic testis with a thick-

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ened and hypoechoic mediastinum. (B) Absence of detectable flow in the mediastinum (arrow) and adjacent area.

occur because the testicle and adnexa are loosely attached to the scrotal wall and to the inguinal canal during the in utero and perinatal periods [7, 12]. The rotation occurs at the external inguinal ring and all hemiscrotal content is strangulated and submitted to extensive ischemic process.

Torsion phases

Fig. 4. Acute torsion of the left spermatic cord in a 17-yearold boy, only 2 h after the onset of symptoms. (A) Enlarged, tender, and reddened left hemi-scrotum. The twisted spermatic cord structures are pulled up into the inguinal region. (B) Longitudinal sonogram of the enlarged mildly hypoechoic torsed left testis surrounded by a small hydrocele.

testicular parenchyma as well as the attachment system of the testis to the scrotal wall and inguinal canal [6]. There are two types of torsion: the intravaginal and the extravaginal torsion of the spermatic cord. The intravaginal type accounts for 65–80% [10] and is related to the bell clapper congenital anomaly where the testis and epididymis are freely suspended in the scrotum, within the tunica vaginalis much like a clapper inside a bell [11]. Intrauterine and neonatal torsions are extravaginal and

The clinical symptoms are traditionally used to classify the torsion of the spermatic cord as ACUTE when they began in less than 24 h [9, 13]. With presentation between 1 to 7 and 10 days, the term SUBACUTE or missed torsion apply [13]. The term CHRONIC torsion is appropriate when symptoms had begun before or persist for more than 10 days [14].

Signs and symptoms 1. Acute onset of scrotal pain, particularly at night. Nausea, vomiting, and sometimes low-grade fever [8]. 2. Prehn’s sign: pain is not relieved with elevation of the testis above the symphysis pubis [15]. 3. Asymmetric enlargement. Swollen, tender, erythematous hemi-scrotum. On the base of the scrotum there may be pitting of the skin (Ger’s sign) [6, 8]. 4. Absence of cremasteric reflex [4], most sensitive physical finding [3]. 5. High-riding testicle (the torsed cord shortens, pulling the testis higher toward the inguinal canal) [5, 15]. 6. Horizontal lie of testis (Brunzel’s sign) [6, 15, 16].

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Fig. 5. Torsion of the spermatic cord with extensive hemorrhagic testicular infarction. (A) Longitudinal sonogram of the left testis. (B) Longitudinal sonogram of the right torsed

testis. Compare the size and echogenicity. The right testis is enlarged and diffusely hyperechoic due to parenchymal bleeding.

Gray-scale aspects of the torsion The diagnosis of acute testicular torsion can be made by a combination of gray-scale imaging and color Doppler sonography [20, 21]. In the torsion of the spermatic cord the gray-scale imaging depends on how many hours or even days have passed on from the clinical onset [11, 22, 23].

Acute and subacute torsion

Fig. 6. Enlargement and nodularization of the infarcted extratesticular components of the affected hemi-scrotum originating the ‘‘hyperechoic paratesticular mass’’ (arrows).

7. Intermittent symptoms or variable scrotal pain (partial torsion or also in the intermittent torsion) [17, 18]. 8. Enlarged, swollen, painless, discolored, nontender, firm, and nontransilluminating scrotal mass (extravaginal torsion) [19].

1. Enlarged testis with a more spherical morphology, demonstrating hypoechogenicity, most frequently diffuse, rarely focal [8, 9, 12] (Fig. 1). Occasionally the testis and epididymis may show a normal sonographic appearance for the first 2–4 h. Special attention must be given, however, to the position of the affected testis in relation to the normal contralateral testis and also to the position of the pair ‘‘mediastinum testis + epididymis’’ in relation to its normal position in the hemi-scrotum. In the setting of an acute TSC with an apparent sonographic normal testis Doppler US is imperative in making the correct diagnosis of torsion. 2. Good identification of the lobar architecture of the affected testis (interstitial and septal edema [24, 25] (Fig. 2).

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Fig. 7. Topographical relation between the torsed testis, the extratesticular mass, and the inguinal canal region. (A) Compound image. A lobulated heterogeneous predominantly echogenic extratesticular mass (EETM) (arrows) detected near the upper pole of the affected testis, at the same side of the mediastinum (MT). (B) The echogenic mass is closer to the inguinal canal (arrow) than the testis. The hydrocele is classically posterior to the torsed testis.

3. When the mediastinum is well identified, it is thickened and less echogenic than the contralateral [14] (Fig. 3). 4. When the normal elliptical morphology is still preserved, the long axis of the testis assumes an oblique or even horizontal position in relation to the long axis of the thigh or the long axis of the femur [4]. If not, the rotation of the testis can be inferred by the abnormal position of the mediastinum [25] (Fig. 4). 5. Diffuse, focal, or multi-focal hyperechogenicity of the testis when the torsion produces a hemorrhagic infarction [9, 12, 26, 27] (Fig. 5). 6. Changes in the epididymis include enlargement and more spherical appearance, with heterogeneous echotexture [14, 23]. When the hemorrhagic infarction also affects the epididymis, it is enlarged and rendered hyperechoic due to the parenchymal bleeding [14] (Fig. 6).

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7. The position of the enlarged and heterogeneous epididymis is also different, now. Although always face-to-face, both epididymis and mediastinum are tractioned to the inguinal canal [14, 25] (Fig. 7). The rotation of the testis can be inferred by the abnormal position of both these structures. In other words, when the affected hemi-scrotum is studied by a transverse craniocaudal scan, the first structure seen immediately below the end of the inguinal canal is the enlarged and heterogeneous epididymis followed by the mediastinum testis [14]. 8. Thickening of the scrotal skin due to the edema (Fig. 8). 9. Reactive hydrocele, after 6 h of the onset [26], posterior to the testis (‘‘ectopic’’ position) [14] (Fig. 7). 10. Relative hyperechogenicity of the testicle surface (tunica albuginea) [14] (Figs. 9 and 10). 11. Marked increase in the soft peritesticular tissues of the hemi-scrotal wall (>5 mm) due to edema [9]. The skin thickening can involve partially the contralateral hemi-scrotum (Fig. 11). 12. In the acute or in the subacute phase of TSC, the reactive effusion may contain internal echoes and scattered fine septations (hematocele) [24, 26] and is shifted to the inferior and posterior aspect of the testis: ‘‘ectopic’’ hydro or hematocele [14] (Fig. 12). 13. Identification of the exact site of the torsion: the spiral aspect of the twisted spermatic cord [12, 19, 22, 26]. The ‘‘torsion knot’’ and the ‘‘whirlpool pattern’’ are highly specific findings of torsion of the spermatic cord [4, 22, 28] including partial testicular torsion. According to Baud et al. [27], however, this sign was seen in only 14 of 23 cases, suggesting low sensitivity and high specificity [29]. This pattern is detected as a lobulated mass in the supratesticular space with concentric layers because of coiling of the cord vessels [22, 23] (Fig. 13). 14. Identification of the torsion adnexial consequences: a large adnexial inhomogeneously echogenic extratesticular mass [26], with a spherical aspect, that contains (a) the enlarged and hemorrhagic epididymis, (b) the caudal segment of the vas deferens—frequently swollen and hemorrhagic, and (c) the collapsed intrascrotal vascular structures distal to the site of the torsion [14]. Sometimes the torsion knot or even this extratesticular mass, subsequently originated below the level of the torsion knot, can be mistaken for an enlarged, tender epididymis, and a diagnosis of epididymitis established with tragic results [4]. Traction of both echogenic mass and the testis to the inguinal region [14] (Fig. 14).

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Fig. 8.

Edema of the scrotal skin. (A) Right torsed testis = 6 mm (arrow) (B) Left normal testis = 3 mm (arrow).

Fig. 9. ‘‘Ectopic’’ reactive hematocele (He) posterior to the affected testis with some echogenic debris in spots. The heterogeneous paratesticular mass (M) also with some hydrocele around (H).

Chronic torsion 15. The hydrocele is absent. 16. The scrotal wall and skin turns to normal. The items [15] and [16] due to the withering of the process. 17. The testis is smaller and harder than the contralateral testis, remaining diffusely hypoechoic [9, 12].

Fig. 10. The hyperechoic ring (arrows) corresponding to the relative hyperechogenicity of the tunica albuginea due to the decreased echogenicity (edema) of the affected testis parenchyma.

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Fig. 11. (A) Torsion of the left spermatic cord in an 18-yearold boy. More than 10 days of symptoms. Enlarged left hemiscrotum and a darkish supra-testicular mass (B) Thickening of the scrotal wall (arrows) caused by edema. A finding pro-

gressively seen during the complete installation of the torsion which can be present 6 h after onset. (C) Intraoperative view. The site of the twisting on the spermatic cord (arrows) and the hemorrhagic and dark necrotic testis.

18. The echogenic mass representing the extratesticular components of the torsion is more compact and organized. The presence of a small echo-poor testis with an echogenic paratesticular nodule is typical of chronic missed torsion [14] (Fig. 15).

demonstration of early perfusion changes [3, 4, 12, 21, 30–32]. This method has a sensitivity of 80–98%, a specificity of 97–100%, and an accuracy rate of 97% [1, 3, 33]. The threshold for color Doppler imaging should be set just above the level for detection of noise, and a highresolution, high-frequency transducer should be used [34]. We found the following signs in our patients:

Doppler aspects of torsion Color Doppler-US is very effective in helping to make or exclude the diagnosis of testicular torsion allowing the

19. Complete absence of detectable flow in the symptomatic testis [7] (Fig. 16) which can be readily distinguished from the normal flow in the contralateral

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remaining testicular blood flow is strongly recommended [14]. 21. Hypervascularity in the thickened scrotal tissues surrounding testis in the scrotal wall [36] (Fig. 18). A small hydrocele is a common finding helping to distinguish flow as not from the surface of the testis.

Power doppler sonography

Fig. 12. The acute or subacute reactive effusion usually contains internal echoes and fine septations that represent the commonly associated hematocele (arrows).

testis or from the hypervascularity found in epididymo-orchitis [3, 9, 23, 35]. 20. Positive blood flow but significantly diminished, usually near or inside the mediastinum [14, 36] (Fig. 17). In this setting spectral analysis of the

Also known as color Doppler energy, color intensity Doppler, color amplitude imaging, amplitude Doppler sonography, and sonographic angiography, the power Doppler method is very sensitive to low flow rates and can help diagnose acute testicular torsion in a newborn infant [17, 20, 37]. Power Doppler sonography has some advantages compared with color Doppler. It is almost independent of the Doppler angle; it is not affected by aliasing and can simultaneously display a wide range of blood flow with lower volumes and lower velocities [37, 38]. Normal testicular blood flow in neonates is very low and difficult to detect by Doppler imaging [20]. Power Doppler sonography is a technique reported to increase the sensitivity in the detection of blood flow by a factor of three to four [39]. In children, power Doppler sonography is more sensitive than color Doppler sonography in the detec-

Fig. 13. Acute right testicular torsion in a 44-year-old man. (A) Observe the spiral aspect of the torsed right spermatic cord. The torsion knot and the whirlpool pattern are potentially highly specific findings of torsion of the spermatic cord. See also Fig. 21A. (B) Compound transverse sonogram of the enlarged and heterogeneous right symptomatic testis (T) and the spiral aspect of the twisted spermatic cord structures (arrows). (C) Compound longitudinal sonogram of the right torsed testis, predominantly hypoechoic with a superior area of hemorrhage (arrows).

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Fig. 14. Chronic testicular torsion in a 14-year-old boy, more than 30 days after the first symptoms. (A) Longitudinal sonogram of the solid heterogeneous paratesticular mass with a spherical aspect that contains the enlarged and hemorrhagic

epididymis, proximal segment of the vas deferens and collapsed intrascrotal vascular structures, distal to the site of the torsion. (B) Transverse sonogram of the torsed testis and the paratesticular mass at the medial side of the testis.

Fig. 15. Chronic testicular torsion in a 15-year-old boy 14 days after the beginning of symptoms. (A) Notice the high position of the right hemi-scrotum elements (M = torsion mass; T = right testis) that were pulled up nearing the inguinal canal. E = left testis location. (B) Longitudinal sonogram of the right torsed testis. (C) Longitudinal sonogram of the left

normal testis, for comparison. The right testis is small (2.3 9 1.5 9 1.4 cm = 2.5 mL), and diffusely hypoechoic. The normal left testis measures 4.2 9 2.3 9 1.8 cm = 9.0 mL. (D) Transverse sonogram of the right testis (T). The echogenic nodule representing the extratesticular components of the torsion is more compact and organized (arrows).

tion of intratesticular blood flow [36, 37]. The literature has noted a few disadvantages of power Doppler sonography, especially lack of information on the direction of flow and the flash artifacts due to the high sensitivity of this technique to small degrees of motion [20]. Power and color Doppler US are complementary modalities [37]. The combination of both methods can be

useful in the exclusion of torsion in most cases saving some patients from unnecessary surgery [17].

Spectral analysis Spectral analysis of the Doppler waveform allows a quantitative assessment of organ perfusion [35]. The spectral waveform analysis of the blood flow to the

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Fig. 16. (A) Longitudinal sonogram of the torsed testis. Complete absence of detectable flow in the symptomatic enlarged and diffusely hypoechoic testis. Notice the strong acoustic attenuation inside the torsed testis probably due to the parenchymal fibrosis. (B) Normal contralateral testis for comparison. It is essential to opti-

mize machine settings by evaluating the nonsymptomatic testis and documenting its normal perfusion before the involved testis is assessed. The analysis must be always compared with the contralateral asymptomatic testis. (C) There is also no detectable flow inside the paratesticular mass.

testis plays an adjunct role in the acute scrotal examination [40]. The normal testis is a low impedance organ. The normal spectral waveform of the testicular artery is a relatively high flow and a low resistance pattern with high levels of diastolic flow [40, 41].

Evaluation of the Doppler waveform obtained in normal testicular arteries yielded an RI of 0.67 ± 0.07 (range 0.50–0.80) [35] or a mean RI of 0.62 (range, 0.48– 0.75) [7]. Arterial flow need not be absent for torsion to be present [22, 31, 40]. Since venous obstruction usually

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precedes arterial obstruction [23] (veins have thinner walls than the arteries and consequently are more sensitive to the compression), the early manifestation of the testicular torsion can be a diminished arterial velocity and a decreased diastolic flow with a consequently increased resistive index, indicating severe obstruction or occlusion to the outflow of blood [22, 40]. Lately the diastolic flow on the affected side can be very low, absent, or even reversed [22]. In summary, these characteristics are useful for the spectral analysis: 22. Increased resistive index (Fig. 19). 23. Absent diastolic flow (Fig. 20). 24. Reversed diastolic flow (Fig. 21). Absent or reversed diastolic arterial flow can also be found in severe epididymitis or epididymo-orchitis with secondary venous outflow obstruction, venous thromboses, and consequently testicular venous infarction [40– 42]. Another possible condition could be a scrotal trauma causing venous occlusion directly or indirectly via a tense intratesticular or extratesticular hematoma [40, 42]. Fig. 17. Torsion of the right spermatic cord in a 16-year-old boy with a 5-day history. He had no previous episodes of scrotal pain. Transverse sonogram of the left painful testis. Only small dots of flow signal are identified on color Doppler images in the spiral knot, near the mediastinum.

Fig. 18. Acute torsion of the right spermatic cord in a 44year-old patient. Longitudinal sonogram. Thickening of the scrotal wall and markedly increased paratesticular blood flow around the nonperfused testis.

Complete, partial, and intermittent torsion Torsion of the spermatic cord can occur in different degrees and present a serious diagnostic challenge. The degree of torsion can vary from one-quarter twist (90°) to up to three complete turns (1080°) of the vascular pedicle. A testis may become nonviable as early as 4 h after a complete 720° tightly compressed torsion or a testis may occasionally remain viable for several days if the torsion is incomplete [43, 44]. Complete torsion usually occurs when the testis twists more than 360° and partial or incomplete torsion when the degree of rotation is less than 360 [8]. In incomplete torsion, the arterial supply is warranted and can be detected as far as the mediastinum testis [8]. The venous flow can be partially or totally obstructed according to the severity of the torsion. Partial torsion may have any of the following patterns: (a) decreased intratesticular flow in relation to the contralateral testis; (b) asymmetry in the spectral Doppler waveform of the testicular artery; (c) absence of a dicrotic notch, resulting in a monophasic waveform; (d) increased resistance to arterial flow due to the decrease in diastolic flow velocities; and (e) reverse diastolic flow when the venous flow is totally obstructed [8, 45]. Intermittent TSC is a syndrome associated with recurrent scrotal pain followed by spontaneous regression of the symptoms due to spontaneous detorsion [16]. Physical findings include a very mobile testis that can be easily inserted into the distal inguinal canal by a digital maneuver or a spontaneous horizontal testis,

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Fig. 19. Complete torsion of the right spermatic cord followed by manual detorsion after 2 h, in a 32-year-old man with scrotal acute pain. (A) On Power Doppler there is only a small dot of flow signal, relatively far from the mediastinum. Observe the hypoechogenicity of the testicular septa due to edema. (B) The

spectral analysis of the Doppler waveform in the torsion knot shows a reversal diastolic flown suggesting acute complete torsion. (C) and (D) After manual detorsion the return of blood flow was verified with color Doppler and Power Doppler sonography. The patient’s discomfort was dramatically alleviated.

sometimes associated with an anteriorly located epididymis. When scanned immediately after the regression of the symptoms the affected testis usually demonstrates a paradoxical increase in the intratesticular blood flow [40]

and a decreased arterial resistance. The testis may be normal in size or may be enlarged. When dislocated to the lumen of the distal inguinal canal by the physician, the symptoms and the color and spectral Doppler signs

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main US guidelines for evaluating patients with acute, subacute, and chronic TSC are demonstrated and discussed including gray-scale, pulsed Doppler US with spectral analysis, and color and power Doppler sonography. References

Gray-scale imaging and color Doppler US are effective in helping to make or exclude the diagnosis of TSC. The

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Fig. 21. Torsion of the right spermatic cord in a 44-yearold man. Same patient as in Fig. 13. (A) There is no detectable blood flow signal inside the torsion knot or in the heterogeneous right testis. (B) Reversed diastolic

flow is present at the right spermatic cord on Doppler spectral examination. When the diastolic flow is reversed, testicular torsion or impending testicular infarction must be considered.

Fig. 20. Torsion of the right spermatic cord in a 16-year-old boy with a 5-day history (same patient as in Fig. 17). Absence of diastolic flow in the mediastinum area of the involved testis.

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